assert(t.typ != nil)
		if !f(t) {
			return false
		}
	}
	return true
}

// underIs calls f with the underlying types of the specific type terms
// of s and reports whether all calls to f returned true. If there are
// no specific terms, underIs returns the result of f(nil).
func (s *_TypeSet) underIs(f func(Type) bool) bool {
	if !s.hasTerms() {
		return f(nil)
	}
	for _, t := range s.terms {

		assert(t.typ != nil)
		if !f(t) {
			return false
		}
	}
	return true
}

// underIs calls f with the underlying types of the specific type terms
// of s and reports whether all calls to f returned true. If there are
// no specific terms, underIs returns the result of f(nil).
func (s *_TypeSet) underIs(f func(Type) bool) bool {
	if !s.hasTerms() {
		return f(nil)
	}
	for _, t := range s.terms {

		case *Slice, *Chan:
			mode = value

		case *Map:
			if id == _Len {
				mode = value
			}

		case *Interface:
			if !isTypeParam(x.typ) {
				break
			}
			if t.typeSet().underIs(func(t Type) bool {
				switch t := arrayPtrDeref(t).(type) {
				case *Basic:
					if isString(t) && id == _Len {
						return true
					}
				case *Array, *Slice, *Chan:
					return true
				case *Map:

		case *Slice, *Chan:
			mode = value

		case *Map:
			if id == _Len {
				mode = value
			}

		case *Interface:
			if !isTypeParam(x.typ) {
				break
			}
			if t.typeSet().underIs(func(t Type) bool {
				switch t := arrayPtrDeref(t).(type) {
				case *Basic:
					if isString(t) && id == _Len {
						return true
					}
				case *Array, *Slice, *Chan:
					return true
				case *Map:

}

// hasNil reports whether type t includes the nil value.
func hasNil(t Type) bool {
	switch u := under(t).(type) {
	case *Basic:
		return u.kind == UnsafePointer
	case *Slice, *Pointer, *Signature, *Map, *Chan:
		return true
	case *Interface:
		return !isTypeParam(t) || u.typeSet().underIs(func(u Type) bool {
			return u != nil && hasNil(u)
		})
	}
	return false
}

}

// hasNil reports whether type t includes the nil value.
func hasNil(t Type) bool {
	switch u := under(t).(type) {
	case *Basic:
		return u.kind == UnsafePointer
	case *Slice, *Pointer, *Signature, *Map, *Chan:
		return true
	case *Interface:
		return !isTypeParam(t) || u.typeSet().underIs(func(u Type) bool {
			return u != nil && hasNil(u)
		})
	}
	return false
}

     in the Source Code under section 3.2; and

     iv) requires any subsequent distribution of the Program by any
     party to be under a license that satisfies the requirements
     of this section 3.

3.2 When the Program is Distributed as Source Code:

  a) it must be made available under this Agreement, or if the

     b. You may distribute such Executable Form under the terms of this License,
        or sublicense it under different terms, provided that the license for
        the Executable Form does not attempt to limit or alter the recipients’
        rights in the Source Code Form under this License.

3.3. Distribution of a Larger Work

     You may create and distribute a Larger Work under terms of Your choice,

    Covered Software available under the terms of the version of the
    License under which You originally received the Covered Software. If
    the Initial Developer includes a notice in the Original Software
    prohibiting it from being distributed or otherwise made available
    under any subsequent version of the License, You must distribute and
    make the Covered Software available under the terms of the version

	// TODO(adonovan): think about generics, and also generic aliases.
	under := aliases.Unalias(typ)
	// Don't call Underlying unconditionally: although it removes
	// Named and Alias, it also removes TypeParam.
	if n, ok := under.(*types.Named); ok {
		under = n.Underlying()
	}
	switch under := under.(type) {
	case *types.Basic:
		switch {
		case under.Info()&types.IsNumeric != 0:
			return &ast.BasicLit{Kind: token.INT, Value: "0"}